Curtailment Or Grid Stability. APTEL Plays Safe in Tata Renewables Plea

In an order pronounced on September 11, the Appellate Tribunal for Electricity (APTEL) has ruled in favour of an APERC order that allowed the Andhra Pradesh State Load Despatch Centre to curtail power from wind energy developers. The curtailment had been done citing grid stability issues, as the transmission line evacuating the power produced was found to be incapable of handling the volumes being produced. The judgement was in response to a suit filed by Tata Power Renewable energy limited, a subsidiary of Tata power.

In effect, APTEL accepted the contention of the state load despatch centre that the curtailment was necessary to prevent a bigger issue should the transmission line in question collapse. However, it is also clear that in situations like this, where the state load despatch centre holds out the risk of a line collapse should its advise be ignored, most regulators will probably side with safety, rather than risk their judgement, however correct in law, from causing an accident. That doesn’t quite sound like justice to anyone actually running the energy assets, in this case, multiple wind energy developers, besides Tata Renewables.

For the issue, that was highlighted by the appellant, (Tata Renewables) was this.

The 400 KV Uravakonda Sub Station, where the power evacuation was happening, had already subjected them to multiple ‘arbitrary’ orders for curtailment since the start of power production.

Starting with an order to limit evacuation to 67% on June 3, 2017, limiting the 100 MW production of Tata to just 67 MW.

On 12.10.2017, APTRANSCO commissioned 315 MVA ICT-4 at Uravakonda GSS, instead of the planned 500 MVA. thus, Tata contended, since the very inception a systematic effort was made to ensure a bottleneck for evacuation of power for RE Generators was created.

On 21.11.2017, APTRANSCO vide its Order directed 72.93% evacuation to all IPPs, including TPREL. On 23.05.2018, a Meeting was held between the APSLDC and various Wind Power Generators, connected to the 400 kV Uravakonda SS, with a cumulative installed capacity of 1755.2 MW. Based on the discussion, it was concluded that  APTRANSCO will explore the construction of 220 kV Borampalli-Kalyandurg line in order to increase evacuation capacity.

Generators agreed to evacuation of up to 90% of Transformers capacity. Accordingly, TPREL’s generation capacity was now restricted to 72.5% instead of agreed 90%.

More curtailment instructions followed during September 2018 to February 2019. However, on 24.02.2019, APTRANSCO revised curtailment from 70.47% to 55.13% for all Wind Generators due to outage availed by 315 MVA ICT-4 to 500 MVA.

TPREL claimed that for the period April 2017 to March 2019, there was a  generation loss of 32.66 MUs, which corresponds to a revenue loss of Rs.17.44 Crores.

Subsequent, to this, even as the line was finally augmented, and generation was allowed back to 79 percent levels, reality was very different. As in between, the state government asked for a renegotiation of rates, where they asked for a rate of Rs 2.43 per unit. when generators went to court, curtailment mysteriously went up again , in essence punishing generators for not complying with dictats.

The state discoms and despatch centre in its defence, has blamed right of way issues for the delay n augmenting the transmission line, and finally, claimed that the risk of higher procurement would be too much. In effect, forcing the apex regulator to go with their decision till the new line comes up. No penalties for delays o any compensation for poor planning at the initial stage itself

For investors in Renewable energy, such judgements highlight the increasing risk of grid stability being used as a crutch to curtail power purchases, despite MNRE instructions to limit curtailment from RE sources. Fresh capacities being set up on promises of appropriate evacuation facilities will also need to be seen more carefully, as clearly, failing to meet the transmission end of the bargain, which is not in the generators control, may not bring anything by way of compensation.

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Prasanna Singh

Prasanna Singh

Prasanna has been a media professional for over 20 years. He is the Group Editor of Saur Energy International